NF770 Temperature Compensation Liquid Flow Computer

Transcription

1 NF770 Temperature Compensation Liquid Flow Computer Overview Mass Flow measurement at a comparatively low cost can be achieved using the Model NF770 Liquid Flow Computer, an RTD temperature sensor and a volumetric flowmeter such as a turbine or positive displacement meter. Volume correction to 15 C or 60 F for petroleum products is also possible. Petroleum tables and equations that comply with API/ASTM standards for metric and US units are included in both instruments. With additional features such as a 10 point non-linearity correction and quadrature pulse input, the Models NF770 is ideally suited to the precise measurement of flow, as required in custody transfer applications. The NF770 Batch Controller displays Batch Total, Preset Quantity, Accumulated Total, Flow Rate, Gross Total and Temperature. Applications General liquids, Petroleums, LPG Features at a glance Displays mass flow, corrected volume flow Accepts 4-20mA and frequency flow inputs Mass Flow calculation Volume Correction for petroleum products Ticket printing option with time and date Simplified programming Data logging Memory & output RS232/RS422/RS485 Communication interface Backlight Display 1

2 Batch Control Selectable protocols on serial ports including Modbus RTU and printer output Two output relays provide control for single or dual stage valve operation. The first relay will energise at the start of the batch and de-energise when the batch is complete. The second relay can be programmed to energise at a set time after the start, and to de-energise at a set quantity prior to completion of the batch. This feature enables a slow start-up and slow shutdown of the flow. The Batch Controller can also be programmed to count up from zero or down from the batch quantity. Batch Operation Four key switches on the front facia, enable the batch quantity to be set, and batch operations to be started, stopped or reset. To set batch quantity, The Batch Set key is pressed, and then the > and ± keys can be used to change and increment digits. Once set, the Batch Set key is again pressed to return to RUN mode. Key operations are straight forward and four LED s indicate the operational status at all times. In the RUN mode, the Display key can be used to display Flow Rate, Gross Total, Accumulated Total and Temperature. The unique four-key operation of the Batch Controller is designed to simplify operation, making the instrument suited to use by operators with minimal training. Batch Functions Batch Total Batching can be performed on the Gross Total, or on the Net Total (or Mass Total). Remote Start/Stop Inputs on rear panel to connect momentary switches to the RUN and STOP keys. Signal Timeout If the flow cuts out midway through a batch, the outputs are de-energised and an alarm signalled. Timeout: 0-999s. Batch Limit The maximum batch limit can be programmed. End of Batch An open collector output signals the end of batch. Auto-Restart The Batch Controller can be programmed to continually repeat batches with a delay of up to 99 minutes between batches 2

3 Specifications General Display 98X23mm Graphic LCD (Backlight) Transducer Supply 8-24V dc field adjustable, 100mA max Power Requirements DC Supply: 14 to 28V dc, 300mA typical (No options) AC Supply: AC mains set internally to V ac or V ac, 50Hz/ 60Hz, 100mA. Operating Temperature 0 to 55 C Dimension 146mm (w) X 75mm (h) X 139mm (d) Panel cutout 139mm (w) X 66.5mm (h) Frequency Input Range Minimum : 0.25Hz on Rate, 0Hz on Total Maximum : 10KHz Input Circuits Accepts most sine, logic and proximity switch inputs, Current Pulses, Meter factor Range to 1000 Non-Linear Correction Up to 10 correction points 4-20mA Inputs Measured Flow (2 ranges), temperature or density Input Impedance 250 ohms Measurement Accuracy : 0.1% Temperature Measurement Ranges General Liquids -273 to 200 (-459 to 392 ). Petroleums -100 to 200 (-148 to 392 ). LPG -45 to 60 (-49 to 140 ). RTD Input Type Platinum PT100 4Wire or 2,3Wire Range -100 C (-148 F) to 200 C (392 F). (Note a wider temperature range can be handled via a 4-20mA input.) Accuracy 0.1 C Linearity The non-linearity of the RTD is internally compensated for Pulse Output Corrected Pulse Pulse Width 10,100, 250, 500ms (negative going pulse) Duty Cycle 50 pulses/sec. max. Uncorrected Pulse Specification of the output is the same as the input. Output Open collector transistor will sink 50mA max. (Note: Suitable for driving remote counters or PLC s.) Current Pulse. ( Only Corrected pulse. ) 4-20mA Output Function Output flow rate in calculated volume, mass and Energy. The 4-20mA Point Resolution 12 Bits Accuracy Better than 0.1% Maximum Load 600 ohms internally powered. Isolation Output is isolated 3

4 RS232/422/485 Type Both RS232 and RS422 are provided. (Note: When using the RS422, multi-point communication (RS485) can be implemented with up to 32 instruments connected to a common bus.) Function Printer and computer protocols are fully programmable Printer A print is initiated on each reset or at a programmable time interval. (Note: Protocols are provided for roll & column printers.) Computer An ASCII based protocol enables all displayed parameters to be read and the totals to be reset Baud Rate : 300 to Data Bits : 7 or 8 Parity : None, Odd or Even Protocol ASCII, MODBUS RTU, MODBUS ASCII Data Logging Output generated at intervals of once a minute to once every 24 hours. The totals can be programmed to reset on each print or at 24:00 hours Time A real time clock is provided to give time and date on each output Relay Ouput Maximum Swiching Power : 1250VA Maximum Swiching Voltage : 250VAC, 30VDC Maximum Swiching Current : 5Amps Options SD Card 2-64GB Potable Data memory Ethernet 10/100 Base-T Ethernet TCP, UDP, IP, ARP, ICMP, MAC, DHCP WiFi IEEE802.11/b/g/n Compatible CDMA External Module(BSM865) Approvals CE, FCC, KC Temperature Compensation Three methods of compensation are built into the instruments with the appropriate method selected during setup. Density Correction Providing a fluid has a known relationship between density and temperature, the density can be determined by measuring the temperature. Up to five temperature and density points can be programmed and the resulting curve is used to determine density. The Mass Flow is then calculated as: Mass Flow = Volumetric Flow x Density The volumetric flow can be accurately determined by turbine, positive displacement or vortex flowmeters. (Note: Non-volumetric inputs from pressure transmitters can also be handled.) 4

5 Volume Correction for Petroleums Volume correction to 15 C or 60 F, as determined by API/ASTM Tables for metric and US units, is possible to the following tables: Crude Oil : Tables 24A and 54A Gasoline, Jet Fuels, Kerosene & Solvents: Tables 24B and 54B Diesel, Heating Oils & Fuel Oils: Tables 24C and 54C LPG : Tables 34 and 54 Volume Correction for General Liquids Volume Correction for General Liquids The thermal co-efficient of expansion can be programmed and a volume corrected flow, to a programmable base temperature, will be calculated as follows: Net Flow = Volumetric Flow 1 + (Tf Tb). a where Tf is the flow temperature ( C or F). Tb is the base temperature ( C or F). a is the thermal co-efficient of expansion. Ordering Information 5

6 Dimension 6